Reducing Project Duration

CHAPTER NINE

Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

McGraw-Hill/Irwin

9–2

Where We Are NowWhere We Are Now

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Rationale for Reducing Project DurationRationale for Reducing Project Duration

• Time Is Money: Cost-Time Tradeoffs–Reducing the time of a critical activity usually incurs

additional direct costs.•Cost-time solutions focus on reducing (crashing)

activities on the critical path to shorten overall duration of the project.

–Reasons for imposed project duration dates:•Time-to-market pressures•Unforeseen delays•Incentive contracts (bonuses for early completion)•Imposed deadlines and contract commitments•Overhead and public goodwill costs•Pressure to move resources to other projects

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Options for Accelerating Project CompletionOptions for Accelerating Project Completion

• Resources Not Constrained–Adding resources–Outsourcing project

work–Scheduling overtime–Establishing a core

project team–Do it twice—fast and

then correctly

• Resources Constrained–Fast-tracking–Critical-chain–Reducing project scope–Compromise quality

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Explanation of Project CostsExplanation of Project Costs

• Project Indirect Costs–Costs that cannot be associated with any particular

work package or project activity.•Supervision, administration, consultants, and interest

–Costs that vary (increase) with time.•Reducing project time directly reduces indirect costs.

• Project Direct Costs–Normal costs that can be assigned directly to

a specific work package or project activity.•Labor, materials, equipment, and subcontractors

–Crashing activities increases direct costs.

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Reducing Project Duration Reducing Project Duration to Reduce Project Costto Reduce Project Cost

Compute total costs for specific durations and Compute total costs for specific durations and compare to benefits of reducing project time.compare to benefits of reducing project time.

Search critical activities for lowest direct-cost Search critical activities for lowest direct-cost activities to shorten project duration.activities to shorten project duration.

Identifying direct costs to reduce project timeIdentifying direct costs to reduce project time

Gather information about direct and indirect Gather information about direct and indirect costs of specific project durations. costs of specific project durations.

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Project CostProject Cost–Duration Graph–Duration Graph

FIGURE 9.1

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Constructing a Project CostConstructing a Project Cost–Duration Graph–Duration Graph

• Find total direct costs for selected project durations.

• Find total indirect costs for selected project durations.

• Sum direct and indirect costs for these selected project durations.

• Compare additional cost alternatives for benefits.

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Constructing a Project CostConstructing a Project Cost––Duration Graph Duration Graph

• Determining Activities to Shorten–Shorten the activities with the smallest increase

in cost per unit of time.

–Assumptions:•The cost relationship is linear.•Normal time assumes low-cost, efficient

methods to complete the activity.•Crash time represents a limit—the greatest time

reduction possible under realistic conditions.•Slope represents a constant cost per unit of

time.•All accelerations must occur within the normal

and crash times.

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Activity GraphActivity Graph

FIGURE 9.2

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CostCost–Duration Trade-off Example–Duration Trade-off Example

FIGURE 9.3

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CostCost–Duration Trade-off Example (cont’d)–Duration Trade-off Example (cont’d)

FIGURE 9.3 (cont’d)

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CostCost–Duration Trade-off Example (cont’d)–Duration Trade-off Example (cont’d)

FIGURE 9.4

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CostCost–Duration Trade-off Example (cont’d)–Duration Trade-off Example (cont’d)

FIGURE 9.4 (cont’d)

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Summary Costs by DurationSummary Costs by Duration

FIGURE 9.5

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Project CostProject Cost–Duration Graph–Duration Graph

FIGURE 9.6

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Practical ConsiderationsPractical Considerations

• Using the Project Cost–Duration Graph

• Crash Times

• Linearity Assumption

• Choice of Activities to Crash Revisited

• Time Reduction Decisions and Sensitivity

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What if Cost, Not Time Is the Issue?What if Cost, Not Time Is the Issue?

• Commonly Used Options for Cutting Costs–Reduce project scope

–Have owner take on more responsibility

–Outsourcing project activities or even the entire project

–Brainstorming cost savings options

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Key TermsKey Terms

CrashingCrash pointCrash timeDirect costsFast-trackingIndirect costsOutsourcingProject cost–duration graph

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Project Priority Matrix: Whitbread ProjectProject Priority Matrix: Whitbread Project

FIGURE 9.6